Use of chymase inhibitors for the prevention and/or treatment of arterio-venous graft failure

ABSTRACT

Disclosed is a method of treating A-V graft failure in a subject in need of such treatment, said method comprising administering to said subject an effective amount of an agent that inhibits the production, release or neo-intima generating effects of chymase, wherein said effective amount of said agent is an amount effective to treat said A-V graft failure.

BACKGROUND OF THE INVENTION

Approximately 100,000 arterio-venous (A-V) vascular access proceduresare performed each year in the US to provide access for the performanceof renal dialysis (Stanley et al., J. Vasc. Surg. 1996, 23, 172-181).The most common material used for prosthetic dialysis access ispolytetrafluoroethylene (PTFE or Gore-Tex), but approximately 60% ofthese grafts fail each year, usually due to stenosis at the venous end(Culp et al., Am. J. Kidney Dis. 1995, 26, 341-346; Churchill et al., J.Am. Soc. Nephrol. 1994, 4, 1809-1813; and Feldman et al., Kidney Int.1993, 43, 1091-1096). Similar lesions develop in PTFE grafts placed intothe arterial circulation, and again there is a tendency for the distalend of the graft to be more effected, but the rate of stenosis is not asgreat as in A-V grafts (Cantelmo et al., J. Cardiovasc. Surg. (Torino)1989, 30, 910-915). Studies have shown that stenosis in A-V grafts isassociated with the proliferation and build-up of smooth muscle cells(Kohler et al., J. Vasc. Surg. 1999, 30, 744-751 and Rekhter et al.,Arterioscler. Thromb. 1993, 13, 609-617).

Percutaneous transluminal coronary angioplasty (PTCA) is an establishedtherapy for obstructive coronary artery diseases. PTCA may beaccomplished by balloon dilation, or more recently by the use ofintracoronary stents. The long-term efficacy of PTCA has been limited bythe occurrence of restenosis (Lin et al., Circulation 1989, 79,1374-1387). Restenosis following PTCA, like the stenosis that occursfollowing A-V graft placement, is characterized by the proliferation andmigration of smooth muscle cells and the subsequent development of aneointima (Lin et al., supra). Angiotensin II has been shown to play arole in neointimal development (Dzau et al., Hypertension. 1991,18(suppl II), II-100-II-105). The involvement of angiotensin II in thepathophysiology of restenosis following PTCA was subsequently confirmedby the demonstration that both angiotensin converting enzyme (ACE)inhibitors and angiotensin II antagonists inhibit neointima developmentfollowing balloon angioplasty (Powell et al., Science 1989, 245, 186-188and Osterrieder et al., Hypertension 1991, 18 (suppl II), II-60-II-64).Based on these observations, ACE inhibitors were used in clinical trialsto prevent restenosis following PTCA, but were found to be ineffective(MERCATOR Study Group, Circulation 1992, 86, 100-110 and Faxon, J. Am.Coll. Cardiol. 1995, 25,362-369).

The failure of ACE inhibitors in clinical trials, in contrast to theirefficacy in animal models, lead to investigations into the source ofthis discrepancy. The source of the discrepancy seemed to be related tospecies differences in angiotensin II formation in humans versus ratsand other species commonly used in animal models of restenosis. WhileACE plays an important role in the production of angiotensin II fromangiotensin I in rat vascular tissue, the primary route for generationof angiotensin II in humans, monkey and dog vascular tissue is chymase(Okunishi et al., J. Hypertens. 1984, 2, 277-284; Okunishi et al.,Biochem. Biophys. Res. Commun. 1987, 149, 1186-1192; Okunishi et al.,Jpn. J. Pharmacol. 1993, 62, 207-210; Shiota et al., FEBS Lett. 1993,323, 239-242; and Takai et al., FEBS Lett. 1997, 421, 86-90). Chymasefrom these species cleaves angiotensin I to produce angiotensin II,while chymase from rats degrades angiotensin I to inactive fragments (LeTrong et al., Proc. Natl. Acad. Sci. USA 1987, 84, 364-3679). Ballooninjury of dog carotid arteries results in significant activation ofvascular tissue chymase levels, but not ACE levels (Shiota et al.,supra). While an ACE inhibitor has little inhibitory effect on thedevelopment of neointima following balloon injury in the dog carotid,significant inhibition of neointima development has been reported withthe use of an angiotensin II receptor antagonist (Okunishi et al., J.Hypertens. 1994, 12(suppl 3), S132).

Chymase is produced primarily in connective tissue mast cells, andsecreted into the interstitium. Some anti-allergenic drugs are capableof stabilizing mast cells, and thus inhibiting the release of chymase bymast cells. Tranilast, (N-(3,4-dimethoxycinnamoyl) anthranilic acid;available from A.G. Scientific, San Diego, Calif.) is an anti-allergydrug that stabilizes mast cells and mast cell degranulation (Okunishi etal., Jpn. J. Pharmacol. 1993, 62, 207-210 and Shiota et al., supra).Tranilast suppresses neointima formation in balloon-injured dog coronaryarteries by suppression of vascular chymase levels (Okunishi et al.,Jpn. J. Pharmacol. 1993, 62, 207-210; Shiota et al., supra; Takai etal., supra; and Le Trong et al., supra). Tranilast was subsequentlyshown upon oral administration over three months in clinical trials tomarkedly reduce the rate of restenosis following PTCA (Takai et al.,supra).

In contrast to Tranilast, which inhibits chymase release by mast cells,NK3201,(2-(5-formylamino-6-oxo-3-phenyl-1,6,-dihydropyrmidine-1-yl)-N-{2,3-dioxo-6-(2-pyridyloxy)-1-phenylmethyl}hexylacetamide) is a direct inhibitor of chymase activity (Takai et al.,Circulation 2001, abstract number 1135; and U.S. Pat. No. 6,271,238).Similar to Tranilast, NK3201 has been shown to inhibit intimalhyperplasia in the dog carotid artery balloon injury model (Takai etal., Circulation 2001, abstract number 1135). In addition, NK3201 hasdemonstrated the ability to inhibit vascular proliferation andsubsequent neointima formation in a dog model of vein graft injury(Takai et al., Life Sci. 2001, 69, 1725-1732). This model consists ofbypass grafting of the carotid artery with a piece of the ipsilateraljugular vein. When the vein tissue is placed into the arteryenvironment, the result is proliferation and neointima formation similarto that observed in the carotid artery balloon injury model.

SUMMARY OF THE INVENTION

The present invention relates to the use of agents that inhibit theproduction, release or neo-intima generating effects of chymase fortreating and/or inhibiting A-V graft failure. Accordingly, in a firstaspect, the invention features a method of treating A-V graft failure ina subject, preferably a human, in need of such treatment that includesadministering an effective amount of an agent that inhibits theproduction, release, or neo-intima generating effects of chymase to thesubject, where the effective amount of the agent is that amounteffective in treating the A-V graft failure. In one embodiment, thegraft failure includes intimal hyperplasia, which can include theproliferation and migration of smooth muscle cells, such as can occur atthe venous end of an A-V graft. Therefore, in another aspect, theinvention features a method of treating intimal hyperplasia associatedwith an A-V graft by administering an agent that inhibits theproduction, release, or neo-intima generating effects of chymase. Anexample of an agent useful for any of the foregoing methods of theinvention is N-(3,4-dimethoxycinnamoyl)anthranilic acid, or apharmaceutically acceptable salt thereof. Other agents useful for any ofthe foregoing methods of the invention include angiotensin II receptorantagonists or chymase inhibitors, such as2-(5-formylamino-6-oxo-3-phenyl-1,6,-dihydropyrmidine-1-yl)-N-{2,3-dioxo-6-(2-pyridyloxy)-1-phenylmethyl}hexylacetamide.

DETAILED DESCRIPTION

A-V graft failure displays intimal hyperplasia at the venous end of thegraft that is similar in composition to that observed in animal modelsof arterial balloon injury and bypass grafting of a vein into an artery.Thus, compounds that show efficacy in these latter models would beuseful in treating and/or inhibiting A-V graft failure. Importantly,although chymotrypsin type proteases have been considered to participatein some fashion in diseases such as asthma, allergy, inflammations,rheumatism, hypertension, heart failure, myocardial infarction, cardiachypertrophy, vascular injuries accompanied by angiogenesis and atheroma,nephritis and renal insufficiency, the use of known inhibitors ofneointimal development in PTCA restenosis models or vein graft stenosismodels, e.g., chymase inhibitors, in the treatment and/or inhibition ofA-V graft failure has not been previously suggested.

Chymase inhibitors are well known to those of skill in the art. Anon-exclusive list of suitable chymase inhibitors would comprise,without limitation, the compounds described in the following references:U.S. Pat. Nos. 6,410,576; 6,372,744; 6,355,460; 6,271,238; 6,159,938;6,080,738; 5,948,785; 5,814,631; 5,723,316; 5,691,335; 5,367,064;5,266,465; 5,079,336; 5,723,316; and 6,271,238. Also well known areassays for determining chymase inhibitory activity (see, e.g., U.S. Pat.Nos. 6,410,576; 6,372,744; 6,355,460; 6,271,238; 5,723,316; 6,080,738;5,948,785; 5,814,631; 5,723,316; and 5,691,335).

Preferred compounds for use in methods according to the invention wouldinclude, without limitation, angiotensin II receptor antagonists, mastcell stabilizing agents, and chymase inhibitors. Particularly preferredcompounds for use in methods according to the invention would includeTRANILAST and NK-3201, and pharmaceutically acceptable salts thereof.The synthesis of NK-3201 is detailed in U.S. Pat. No. 6,271,238 (seesynthesis example No. 55 therein).

Compounds for use in methods according to the invention can beformulated and administered to a subject using the guidance providedherein along with techniques well known in the art. The preferred routeof administration ensures that an effective amount of compound reachesthe target. Guidelines for pharmaceutical administration in general areprovided in, for example, Remington: The Science and Practice ofPharmacy 20^(th) Edition, Ed. Gennaro, Lippincott, Williams & WilkinsPublishing, 2000, which is hereby incorporated by reference herein.

Pharmaceutical compositions for use in the method of the invention maybe formulated such that the pharmaceutically active compound is usedalone or mixed with excipients or carriers and administered orally orparenterally such as by an injection, inhalant, tablets, granules,subtle granules, powder, capsules, suppositories, instillations, pasteagents, ointments, sprays etc. As excipients or carriers,pharmaceutically acceptable additives are selected and the type andcomposition are determined according to the administration route andadministration method. For example, in the case of an injection, sodiumchloride or saccharides such as glucose, mannitol etc. is generallypreferable. In the case of oral preparations, starch, lactose,crystalline cellulose, magnesium stearate etc. are preferable.

The content of the pharmaceutically active compound in a pharmaceuticalcomposition varies depending on the preparation, but is usually in therange of 0.1% to 100% by weight, preferably 1% to 98% by weight. Forexample, in the case of an injection, the active ingredient is containedin the range of usually 0.1% to 30% by weight, preferably 1% to 10% byweight. In the case of an oral preparation, the pharmaceutically activecompound is used with additives in the form of tablets, capsules,powder, granules, liquid, dry syrup etc. The capsules, tablets, granulesand powder contain generally 5% to 100% by weight of thepharmaceutically active compound, preferably 25% to 98% by weight.

In general, an effective dosage of active ingredient may be varied.However, it is necessary that the amount of the active ingredient besuch that a suitable dosage form is obtained. The selected dosagedepends upon the desired therapeutic effect, on the route ofadministration, and on the duration of the treatment, all of which arewithin the realm of knowledge of one of ordinary skill in the art.Generally, dosage levels of between 0.0001 mg/kg to 100 mg/kg of bodyweight daily are administered to humans or other animals, e.g., mammals.A preferred dosage range is 0.01 mg/kg to 100.0 mg/kg of body weightdaily, more preferably 1.0 mg/kg to 10.0 mg/kg of body weight daily,which can be administered as a single dose or divided into multipledoses, or provided for continuous administration.

Further, an effective dosage of active ingredient may be administered ina sustained release composition such as those described in the followingpatents: U.S. Pat. No. 5,672,659 teaches sustained release compositionscomprising a bioactive agent and a polyester; U.S. Pat. No. 5,595,760teaches sustained release compositions comprising a bioactive agent in agelable form; U.S. application Ser. No. 08/929,363, filed Sep. 9, 1997,teaches polymeric sustained release compositions comprising a bioactiveagent and chitosan; U.S. application Ser. No. 08/740,778, filed Nov. 1,1996, teaches sustained release compositions comprising a bioactiveagent and cyclodextrin; and U.S. application Ser. No. 09/015,394, filedJan. 29, 1998, teaches absorbable sustained release compositions of abioactive agent. The teachings of the foregoing patents and applicationsare incorporated herein by reference.

Other features and advantages of the present invention will be apparentfrom the present description and also from the claims. It is believedthat one skilled in the art can, based on the description herein,utilize the present invention to its fullest extent. The followingspecific embodiments are therefore to be construed as merelyillustrative and not limitative of the remainder of the disclosure inany way whatsoever. All of the documents cited herein are herebyincorporated by reference in their entirety.

From the above description, one skilled in the art can easily ascertainthe essential characteristics of the present invention, and withoutdeparting from the spirit and scope thereof, can make various changesand modifications of the invention to adapt it to various uses andconditions. Thus, other embodiments are also within the claims.

1. A method of treating A-V graft failure in a subject in need of suchtreatment, said method comprising administering an effective amount ofan agent that inhibits the production, release, or neo-intima generatingeffects of chymase to said subject, wherein said effective amount ofsaid agent is an amount effective to treat said A-V graft failure.
 2. Amethod according to claim 1 wherein said A-V graft failure comprisesintimal hyperplasia.
 3. A method of treating intimal hyperplasiaassociated with an A-V graft, said method comprising administering anagent that inhibits the production, release or neo-intima generatingeffects of chymase.
 4. A method according to claim 1, wherein said agentis N-(3,4-dimethoxycinnamoyl)anthranilic acid, or a pharmaceuticallyacceptable salt thereof.
 5. A method according to claim 1, wherein saidagent is an angiotensin II receptor antagonist.
 6. A method according toclaim 1, wherein said agent is a chymase inhibitor.
 7. A methodaccording to claim 6, wherein said chymase inhibitor is2-(5-formylamino-6-oxo-3-phenyl-1,6,-dihydropyrmidine-1-yl)-N-{2,3-dioxo-6-(2-pyridyloxy)-1-phenylmethyl}hexylacetamide, or a pharmaceutically acceptable salt thereof.
 8. A methodaccording to claim 1, wherein said subject is human.
 9. A methodaccording to claim 1, wherein said treatment comprises inhibition ofintimal hyperplasia.
 10. A method according to claim 9, wherein saidintimal hyperplasia comprises the proliferation and migration of smoothmuscle cells.
 11. A method according to claim 9, wherein said intimalhyperplasia occurs at the venous end of said A-V graft.
 12. A methodaccording to any one of claims 8-11, wherein said agent is2-(5-formylamino-6-oxo-3-phenyl-1,6,-dihydropyrmidine-1-yl)-N-{2,3-dioxo-6-(2-pyridyloxy)-1-phenylmethyl}hexylacetamide, or a pharmaceutically acceptable salt thereof.